Each column keeps its native condition scope. Initial features are displayed alphabetically, not ranked by clinical importance. Counts remain separate, and an empty cell does not mean a feature cannot occur.
"},"coverage":{"countRecords":0,"emptyColumnKeys":[],"hpoRelease":"2026-06-23","narrativeSourceChanges":[],"records":3,"sourceGroups":{"omim":3,"orphanet":0,"published":0}},"features":[{"hpoId":"HP:0001880","label":"Increased total eosinophil count","primary":false},{"hpoId":"HP:0006782","label":"Malignant eosinophil proliferation","primary":false},{"hpoId":"HP:0005547","label":"Myeloproliferative disorder","primary":false}],"ledeHtml":"PDGFRB-associated chronic eosinophilic leukemia is a type of cancer of blood-forming cells. It is characterized by an elevated number of white blood cells called eosinophils in the blood. These cells help fight infections by certain parasites and are involved in the inflammation associated with allergic reactions. However, these circumstances do not account for the increased number of eosinophils in PDGFRB-associated chronic eosinophilic leukemia. Some people with this condition have an increased number of other types of white blood cells, such as neutrophils or mast cells, in addition to eosinophils. People with this condition can have an enlarged spleen (splenomegaly) or enlarged liver (hepatomegaly). Some affected individuals develop skin rashes, likely as a result of an abnormal immune response due to the increased number of eosinophils.","mondoId":"MONDO:0007546","records":[{"frequencyKind":"reported","key":"77260174a2b1a0583c323480aab37110561d75eabd25f179444ad836565aa42f","raw":{"aspect":"P","body_system":"blood","disease_id":"OMIM:131440","disease_name":"Myeloproliferative disorder, chronic, with eosinophilia","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0005547","is_excluded":false,"label":"Myeloproliferative disorder","onset_id":null,"reference":"OMIM:131440","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"a7e323692faf626a516a0f98a2543c477f9a6bd6648db1b3f91155e5357937ca","raw":{"aspect":"P","body_system":"blood","disease_id":"OMIM:131440","disease_name":"Myeloproliferative disorder, chronic, with eosinophilia","evidence":"IEA","frequency_raw":null,"hpo_id":"HP:0001880","is_excluded":false,"label":"Increased total eosinophil count","onset_id":null,"reference":"OMIM:131440","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"ff0edf96799810b8216ac97a5fc0fa40e9670a5ed8d19814a5c7aa52eb9de668","raw":{"aspect":"P","body_system":"blood","disease_id":"OMIM:131440","disease_name":"Myeloproliferative disorder, chronic, with eosinophilia","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0006782","is_excluded":false,"label":"Malignant eosinophil proliferation","onset_id":null,"reference":"OMIM:131440","source_release":"2026-06-23"},"sourceGroups":["omim"]}],"referenceLabels":{},"references":{"causeHtml":"","identityNote":"MONDO cross-references identify native condition entries. Ancestor membership does not transfer phenotype values between groups.","importantHtml":""},"sections":[{"bodyHtml":"PDGFRB-associated chronic eosinophilic leukemia is caused by genetic rearrangements that join part of the PDGFRB gene with part of another gene. At least 20 genes have been found that fuse with the PDGFRB gene to cause PDGFRB-associated chronic eosinophilic leukemia. The most common genetic abnormality in this condition results from a rearrangement (translocation) of genetic material that brings part of the PDGFRB gene on chromosome 5 together with part of the ETV6 gene on chromosome 12, creating the ETV6-PDGFRB fusion gene.
The PDGFRB gene provides instructions for making a protein that plays a role in turning on (activating) signaling pathways that control many cell processes, including cell growth and division (proliferation). The ETV6 gene provides instructions for making a protein that turns off (represses) gene activity. This protein is important in development before birth and in regulating blood cell formation. The protein produced from the ETV6-PDGFRB fusion gene, called ETV6/PDGFRβ, functions differently than the proteins normally produced from the individual genes. Like the normal PDGFRβ protein, the ETV6/PDGFRβ fusion protein turns on signaling pathways. However, the fusion protein does not need to be turned on to be active, so the signaling pathways are constantly turned on (constitutively activated). The fusion protein is unable to repress gene activity regulated by the normal ETV6 protein, so gene activity is increased. The constitutively active signaling pathways and abnormal gene activity increase the proliferation and survival of cells.
When the ETV6-PDGFRB fusion gene variant (also known as a mutation) occurs in cells that develop into blood cells, the growth of eosinophils (and occasionally other blood cells, such as neutrophils and mast cells) is poorly controlled, leading to PDGFRB-associated chronic eosinophilic leukemia. It is unclear why eosinophils are preferentially affected by this genetic change.
","key":"forms","title":"What causes PDGFRB-associated chronic eosinophilic leukemia?"},{"bodyHtml":"Source: MedlinePlus Genetics
","key":"overview","title":"Condition overview"}],"sharedSources":[],"slug":"pdgfrb-associated-chronic-eosinophilic-leukemia","sourceDocuments":[{"name":"PDGFRB-associated chronic eosinophilic leukemia","reviewed":"2013-02","sections":{"causes":{"fetchedAt":"2026-10-20T20:24:06.299583+00:00","label":"Causes","pageSha256":"ee1fab9910d1b12b161ac659d8a26664e1ed216b14876c64a87fb25190c8dc16","sourceUrl":"https://medlineplus.gov/genetics/condition/pdgfrb-associated-chronic-eosinophilic-leukemia/#causes","status":"available"}},"source_release":"2026-10-01","url":"https://medlineplus.gov/genetics/condition/pdgfrb-associated-chronic-eosinophilic-leukemia"}],"sourceNote":"MedlinePlus descriptions and Causes; original HPO annotations.","takeawayHtml":"Cause explanations are from MedlinePlus Genetics. Feature values below retain their original sources and patient groups.","title":"PDGFRB-associated chronic eosinophilic leukemia"},"schemaVersion":1}